The field of the present invention relates to data reading systems. In particular, a method and apparatus are described herein for creating an optical code scanner with a wide range of reading distances.
Longer range scanners have been proposed of a variety configurations. In U.S. Pat. No. 5,869,827 multiple beam sources and distance sensing mechanisms are employed to provide an extended focus range. In U.S. Pat. No. 5,641,958 as employed in the PSC SP400LR scanner, an LCD diffractive control module changes the waist location of the scanning beam. In U.S. Pat. No. 4,560,862 the facets of a polygon mirror are provided with different curvatures such that the scan lines produced by the different facets are focused at varying distances.